1. Field of the Invention
The present invention appertains in general to new and novel improvements in oil or gas-fired appliances, including forced combustion wood burning appliances and fireplaces, stoker coal-fired heating plants and warm-air furnaces, boilers and water heaters, and particularly relates to a new and novel system for venting such appliances.
2. State of the Art
The present invention, in particular, relates to new and novel improvements in my prior U.S. Pat. No. 4,079,727 issued Mar. 21, 1978.
Known venting systems function to evacuate combustion products, which may contain carbon monoxide, from the appliance through the flue outlet to the chimney. The venting systems generally incorporate a draft hood or diverter which functions to: (1) provide for the ready escape of the products of combustion in the event of no draft, back draft, or stoppage beyond the draft hood (blocked chimney); (2) prevent a back draft from entering the appliance; and (3) neutralize the effect of stack action (up draft) of the chimney flue upon the operation of the appliance.
During the burn cycle of the appliance, such conventional venting systems do nothing to slow down the velocity of the heat traveling through the appliance's heat exchanger, which results in considerable loss of this heat up through the chimney flue. Nor do they do anything to reduce the volume of excess air drawn into the combustion chamber which dilutes or weakens the heat produced in the flame and also is the principal reason for less than ultimate combustion efficiency. Consequently, more combustion of fuel is required to perform the function of the appliance.
During the appliance's off cycle, such conventional venting systems do nothing to "lock in" the pilot heat and residual heat in the appliance.
Such means as automatic vent dampers have been used to retain some of the pilot heat and residual heat in the off cycle, but these employ electrical and/or mechanical means of operation.
None of the known venting systems deals with the dual facets of safe performance and conservation of fuel. In conventional methods of venting appliances, (1) heat is always permitted to travel very rapidly through the heat exchanger and up the chimney flue; (2) large volumes of excess air are permitted to be drawn into the combustion chamber; and (3) the loss of pilot heat and residual heat from the appliance in the off cycle is permitted, except when electrically and/or mechanically operated automatic vent dampers are used.
Furthermore, stationary internal baffles within known venting systems are utilized only to deflect the flow of flue gases and/or the flow of the air through the relief opening induced by the chimney flue and none of these serve to form a "heat lock" which reduces the velocity of the heat moving through the appliance during the burn cycle, allowing more time for absorption of the heat by the heat exchanger. Nor do they serve to control the volume of excess air drawn into the combustion chamber which weakens the heat and lowers combustion efficiency during the burn cycle.
In addition, such stationary baffles do not serve to form a "heat lock" which stops the loss of pilot heat and residual heat from the appliance in the off cycle.
None of the conventional venting systems reduce the vent pipe temperature. And overheated vent pipes cause most, if not all, flue fires. Also, known venting systems do nothing to counteract blockages of chimney flues.
In prior U.S. Pat. No. 4,079,727 an exterior diverter box is provided and is formed with a vertical baffle that divides the interior of the diverter box into a flue gas inlet section connected to the appliance and a flue gas outlet section connected to the chimney flue. The baffle is disposed well above the lower entirely open end of the box which end lies in a horizontal plane above or, at least, in the same plane in which the bottom of the factory diverter box within the furnace is disposed when the furnace is manufactured or in some instances such as water heaters, 34" above the burner ports, or lower if determined by instrument tests to allow carbon monoxide free combustion under blocked flue conditions.